If you continue to attack Uke's centre, you will automatically move in Sankaku Irimi as Uke wards you off due to inertia, vector motion, and the fact that your movement will be incremental. But then, Uke will be 90 degrees and behind if they do a Tenkai. You want to get to 90 degrees and behind so you then have to do a Tenkan. Depending on who moves faster and has better motion, one or the other will get 90 degrees and behind and have the physical advantage. The winner of that competition will have to quickly transition to a technique to take advantage of the superior position or the result will be another standoff and the start of another series of motions.